A biodiesel manufacturing process by esterification using bio-based raw materials is known as prior art. More precisely, the manufacturing process is transesterification, wherein triglyceride is converted to ester. When manufacturing biodiesel from vegetable oils, triglycerides react with alcohol to form glycerol and alkyl esters, such as methyl esters, of fatty acids. In the manufacturing process, triglyceride is gradually converted to diglyceride, monoglyeride and finally, to glycerol. Regarding esterification, water contained in the raw material is detrimental, because together with the base, which is used as catalyst, and fats, it forms soap instead of biodiesel. Since biological raw materials often contain variable quantities of water, water must be first completely separated from the raw material before the raw material is usable for esterification. This increases the costs of the process and reduces the total economy of the manufacture.
In prior art processes, water wash is normally used to remove acid residues from the finished biodiesel; this consumes remarkable quantities of clean, potable water. In addition, removing residues of water from the finished biodiesel consumes a lot of energy.
Publication US 2008/0221344 A1 proposes a process for producing liquid biofuel from bio-based oils and/or fats by transesterification at high pressures and temperatures. In the process, a catalyst can be used for improving the reaction; however, this is not recommended due to a difficult catalyst separation step. This slows down the reaction and makes the process inefficient.